The present invention relates to the removal of organic solvents from aqueous process streams, which is involved in many industrial processes. The invention will be described in detail in connection with copper leaching and electrowinning processes.
The common leaching process for the recovery of copper from ore involves applying a leaching solution to the ore to produce a pregnant leach which includes copper sulfate. The pregnant leach is mixed with an organic solvent to transfer copper ions to the solvent, the copper ions later being transferred to an electrolyte from which they can be electroplated out. In the transference of copper ions from the pregnant leach to the solvent, some solvent remains behind with the leach solution (referred to as raffinate after the copper ions have been removed). Also, in the transference of copper ions from the solvent to an electrolyte (from which the copper is plated out) some solvent transfers to the electrolyte. Because of the relatively high cost of the solvent, steps are taken to remove the solvent so it can be reused. Prior art techniques for the removal of organic solvents from aqueous process streams in the leach mining of copper ores, are described in U.S. Pat. No. 4,874,534 by Sorenson et al. Systems which enhanced the removal of the solvent would be of considerable value in leach mining of copper and other metals, as well as in other industrial processes.